CN115606069A - Power supply system - Google Patents

Abstract

A power supply system (100), the power supply system comprising: an electrical load (34, 36); a first system (ES 1) including a first power supply (10, 12, 14); a second system (ES 2) including a second power supply (16); and an inter-system switch (SW 1), the first power supply outputting a power supply voltage, the second power supply including a storage battery (16), the power supply system including: an abnormality determination unit that determines whether or not an abnormality has occurred in the first system; and a state control unit that turns off the inter-system switch when the abnormality determination unit determines that an abnormality has occurred, wherein a first path (LC 1) and a second path (LC 2) are provided in parallel with each other between a connection Point (PB) of the second system that is connected to the connection path and the second power supply, wherein the first path is provided with a power converter (26), and wherein the second path is capable of applying the voltage of the battery to the electrical load while bypassing the power converter.

Description

Power supply system

Citation of related applications

This application is based on Japanese patent application No. 2020-083848, filed on 12/5/2020, the contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to a power supply system.

Background

In recent years, there has been known a power supply system which is applied to a vehicle, for example, and supplies electric power to various devices of the vehicle. In this power supply system, when the vehicle is traveling, an abnormality occurs in a system that supplies electric power to an electric load that performs a function required for traveling of the vehicle, such as an electric brake device or an electric power steering device, and thus if the function is lost, the traveling of the vehicle cannot be continued. In order to prevent a function from being lost even when an abnormality occurs while a vehicle is traveling, a device including a first power supply and a second power supply as power supplies for supplying electric power to an electric load is known.

As a power supply system applied to this device, for example, in patent document 1, a power supply system having a first system including a first power supply as a high-voltage power supply and a second system including a second power supply as a low-voltage power supply is known. In this power supply system, an inter-system switch is provided in a connection path for connecting each system. A DCDC converter (hereinafter, simply referred to as a converter) is provided between the connection point of the second intra-system path to the connection path and the second power supply side, and the second power supply can be charged by the converter. When it is determined by the controller that an abnormality has occurred in the first system, the inter-system switch is closed, and electric power is supplied from the second power supply to the electric load by discharging of the second power supply by the converter. That is, by supplying electric power to the electric load from the second power supply of the second system in which no abnormality has occurred, it is possible to continue the traveling of the vehicle while ensuring the functions necessary for the traveling of the vehicle.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2019-30116

Disclosure of Invention

However, since the converter performs power conversion at the time of discharge, the discharge is started after the preparation process for power conversion. Therefore, a predetermined period is required from the start of the preparation process to the actual start of the discharge, and there is a possibility that appropriate power supply to the electric load cannot be performed during the predetermined period.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a power supply system capable of appropriately supplying power to an electric load in a power supply system having a plurality of power supply systems.

A first aspect for solving the above-described problems is a power supply system including: an electrical load; a first system including a first power source connected to the electrical load; a second system including a second power source connected to the electrical load; and an inter-system switch provided in a connection path connecting the first system and the second system to each other, wherein the first power supply outputs a power supply voltage capable of driving the electric load, and the second power supply includes a battery capable of being charged by the power supply voltage of the first power supply, and the power supply system includes: an abnormality determination unit that determines whether or not an abnormality has occurred in the first system; and a state control unit configured to turn off the inter-system switch when it is determined by the abnormality determination unit that an abnormality has occurred, wherein a first path and a second path are provided in parallel with each other between a connection point of the second system, which is connected to the connection path, and the second power supply, a power converter configured to convert power between charging of the storage battery by power supply from the first power supply and discharging of the storage battery is provided in the first path, the storage battery is charged to a voltage higher than a lower limit value of a drive voltage of the electrical load by the power converter, and the voltage of the storage battery can be applied to the electrical load by bypassing the power converter in the second path.

According to the above structure, there are provided the first system including the first power supply and the second system including the second power supply. Therefore, the power supply load can be supplied with redundant power by the first power supply and the second power supply. In addition, an inter-system switch is provided in a connection path connecting the first system and the second system to each other. Therefore, when it is determined that an abnormality has occurred in one of the systems, the inter-system switch is turned off, whereby the operation of the electrical load can be continued by the supply of power from the power supply of the other system in which no abnormality has occurred.

Here, for example, when the inter-system switch is turned off in association with the occurrence of an abnormality in the first system, the discharge of the storage battery from the second power supply by the power converter is performed in the second system, but in the power converter that performs power conversion at the time of discharge, the discharge is started after the preparation process for power conversion. Therefore, a predetermined period is required from the start of the preparation process to the actual start of the discharge, and there is a possibility that appropriate power supply to the electric load cannot be performed during the predetermined period.

In this regard, in the above configuration, a first path and a second path are provided in parallel with each other between the connection point connected to the connection path in the second system and the second power supply, and the battery is charged or discharged at a voltage higher than the lower limit value of the drive voltage of the electric load by the power conversion of the power converter in the first path. In the second path, the voltage of the battery can be applied to the electric load bypassing the power converter. In this case, when the second system supplies electric power from the battery in association with the occurrence of an abnormality in the first system, the battery of the second power supply is charged to a voltage higher than the lower limit value of the driving voltage of the electric load, and the voltage can be applied to the electric load bypassing the electric power converter during a predetermined period required for power conversion by the electric power converter. This enables appropriate power supply to an electric load in a power supply system having a plurality of power supply systems.

In a second aspect, the second path is provided with a battery switch for opening or closing the second path, the power converter performs or stops charging or discharging of the storage battery in accordance with a command from the state control unit, the state control unit opens the inter-system switch and outputs a command for performing discharging of the storage battery to the power converter when the abnormality determination unit determines that an abnormality has occurred, and the battery switch is closed for a predetermined period including a period from when the command is output to when the discharging of the storage battery is started.

In the above configuration, the second path is provided with a battery switch, and the battery switch is closed in association with output of a discharge command to the power converter when an abnormality occurs in the first system. Specifically, the battery switch is closed during a predetermined period including a period from the output of a command to discharge the battery to the power converter to the start of the discharge operation. Thus, when an abnormality occurs in the first system, appropriate power supply to the electric load is enabled.

In a third aspect, the power converter performs a boosting operation of boosting a voltage of the battery when the battery is discharged, and the state control unit turns off the battery switch after the discharge of the battery is started.

In a configuration in which the voltage of the electrical load is made higher than the voltage of the battery when the battery is discharged, if the battery switch is closed after the discharge of the battery is started, the voltage rise of the electrical load may be delayed or the voltage of the electrical load may become unstable due to the charging of the battery via the second path. In this regard, in the above configuration, since the battery switch is turned off after the discharge operation is started, the voltage of the electrical load can be appropriately increased.

In a fourth aspect, the power converter performs a step-down operation of stepping down a voltage of the battery when the battery is charged and performs a step-up operation of stepping up the voltage of the battery when the battery is discharged, and the second path is provided with a rectifier element that restricts a current flowing from the connection point to the battery in the second path.

In a configuration in which the voltage of the battery is lower than the power supply voltage when the battery is charged, a rectifier element is provided in the second path, and the rectifier element restricts the flow of current from the connection point to the battery in the second path, so that the power supply system can be configured using a battery having a rated voltage lower than the power supply voltage. In addition, when an abnormality occurs in the first system, the second system discharges the electric power from the battery with a decrease in the voltage on the electric load side, and the electric power can be supplied to the electric load in advance without waiting for a predetermined period required for the step-up operation of the power converter when the battery discharges.

In a fifth aspect, a semiconductor switching element having a parasitic diode, which is the rectifying element, is provided in the second path, and the state control unit turns on the semiconductor switching element when the abnormality determination unit determines that an abnormality has occurred.

In the configuration using the parasitic diode of the semiconductor switching element as the rectifying element, when an abnormality occurs in the first system, power can be supplied from the battery to the electric load via the parasitic diode, but a voltage drop occurs due to the forward voltage drop amount of the parasitic diode. In addition, the parasitic diode may generate heat by the conduction. In this regard, in the above configuration, when an abnormality occurs in the first system, since the semiconductor switching element is in the on state, it is possible to output a voltage to the electrical load in advance and suppress a voltage drop due to a forward voltage drop amount of the parasitic diode. In addition, heat generation of the parasitic diode can be suppressed.

In a sixth aspect, the power supply system is mounted on a vehicle, wherein the electrical load is a load that performs at least one function required for traveling in the vehicle and that performs a driving assistance function of the vehicle, the vehicle is capable of traveling in a first mode in which the driving assistance function is used and traveling in a second mode in which the driving assistance function is not used, and the power supply system includes a mode control unit that allows the traveling mode of the vehicle to be shifted from the second mode to the first mode on condition that a state of charge of the battery is higher than a lower limit value of a driving voltage of the electrical load.

In a power supply system applied to a vehicle having an electrical load for performing a function necessary for traveling and performing a driving assistance function, traveling in a first mode in which the driving assistance function is used and traveling in a second mode in which the driving assistance function is not used can be switched. Here, in the above configuration, the vehicle travel mode is permitted to shift from the second mode to the first mode on the condition that the state of charge of the battery is in a state in which the voltage of the battery is higher than the lower limit value of the drive voltage of the electrical load. Therefore, even if an abnormality occurs in the first system after the shift to the first mode, appropriate fail-safe processing can be performed thereafter.

Drawings

The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. The drawings are as follows.

Fig. 1 is an overall configuration diagram of a power supply system of the first embodiment.

Fig. 2 is a flowchart showing the procedure of the control processing of the first embodiment.

Fig. 3 is a timing chart showing an example of the control processing according to the first embodiment.

Fig. 4 is an overall configuration diagram of a power supply system of the second embodiment.

Fig. 5 is a flowchart showing the steps of the control processing of the second embodiment.

Fig. 6 is a timing chart showing an example of the control processing of the second embodiment.

Fig. 7 is an overall configuration diagram of a power supply system according to another embodiment.

Detailed Description

(first embodiment)

Hereinafter, an embodiment of a power supply system 100 embodying the power supply system of the present disclosure as a vehicle will be described with reference to the drawings.

As shown in fig. 1, the power supply system 100 is a system that supplies power to a general load 30 and a specific load 32. Power supply system 100 includes a high-voltage battery 10, a first DCDC converter (hereinafter referred to as a first converter) 12, a first battery 14, a second battery 16, a switching unit 20, a second DCDC converter (hereinafter referred to as a second converter) 26, and a control device 40.

The high-voltage battery 10 has a higher rated voltage (for example, several hundred V) than the first battery 14 and the second battery 16, and is, for example, a lithium-ion battery. The first converter 12 is a voltage generator that converts the electric power supplied from the high-voltage battery 10 into electric power of the power supply voltage VA and supplies the electric power to the general load 30 and the specific load 32. In the present embodiment, power supply voltage VA is a voltage capable of driving general load 30 and specific load 32.

The general load 30 is an electric load (hereinafter, simply referred to as a load) that is not used for travel control in a vehicle as a moving body, and is, for example, an air conditioner, an audio device, a power window, or the like.

On the other hand, the specific load 32 is a load that performs at least one function for running control of the vehicle, and is, for example, an electric power steering device 50 that controls steering of the vehicle, an electric brake device 51 that applies a braking force to wheels, a running control device 52 that monitors the conditions around the vehicle, and the like. In the present embodiment, the specific load 32 corresponds to an "electrical load".

Therefore, if an abnormality occurs in these specific loads 32 and all of their functions are lost, the running control cannot be performed. Therefore, the specific load 32 has a first load 34 and a second load 36 provided redundantly for each function so as not to lose all of its functions even when an abnormality occurs. Specifically, the electric power steering device 50 has a first steering motor 50A and a second steering motor 50B. The electric brake device 51 has a first brake device 51A and a second brake device 51B. The travel control device 52 includes a camera 52A and a laser radar 52B. The first steering motor 50A, the first brake device 51A, and the camera 52A correspond to the first load 34, and the second steering motor 50B, the second brake device 51B, and the laser radar 52B correspond to the second load 36.

The first load 34 and the second load 36 together implement one function, but even if used individually, can implement a part of the function. For example, in the electric power steering apparatus 50, the first steering motor 50A and the second steering motor 50B can freely steer the vehicle, and when there is a certain limitation in the steering speed, the steering range, and the like, the steering of the vehicle can be performed by the steering motors 50A, 50B.

Each specific load 32 realizes a function of assisting the control by the driver in the manual driving. Each specific load 32 realizes a function required for automatic driving in which an operation such as running or stopping of the vehicle is automatically controlled. Therefore, the specific load 32 may also be referred to as a load that performs at least one function required for the vehicle to travel.

The first load 34 is connected to the first converter 12 via a first intra-system path LA1, and the first battery 14 and the general load 30 are connected to the first intra-system path LA 1. The first battery 14 is, for example, a lead battery. In the present embodiment, the first converter 12, the first battery 14, the general load 30, and the first load 34 connected via the first intra-system path LA1 constitute a first system ES1. In the present embodiment, the high-voltage battery 10, the first converter 12, and the first battery 14 correspond to a "first power supply".

The second load 36 is connected to the second battery 16 via a second intra-system path LA 2. The second battery 16 is, for example, a lithium ion battery. The rated voltage of the second battery 16 is set to a voltage lower than the power supply voltage VA of the first converter 12. In the present embodiment, the second battery 16 and the second load 36 connected through the second intra-system path LA2 constitute a second system ES2. In the present embodiment, the second battery 16 corresponds to a "second power supply and a battery".

The switch unit 20 is provided in a connection path LB connecting the systems to each other. One end of the connection path LB is connected to the first intra-system path LA1 at a connection point PA, and the other end of the connection path LB is connected to the second intra-system path LA2 at a connection point PB. The switch section 20 includes a first switch element (hereinafter, simply referred to as a first switch) SW1. In the present embodiment, an N-channel MOSFET (hereinafter, abbreviated as MOSFET) is used as the first switch SW1. In the present embodiment, the first switch SW1 corresponds to an "inter-system switch".

The connection path LB is provided with a current detection unit 28. The current detection unit 28 is provided in a portion of the connection path LB closer to the first system ES1 than the switch unit 20, and detects the magnitude and direction of the inter-system current IA flowing through the portion.

The second switch 26 is provided in the second intra-system path LA 2. Specifically, the second converter 26 is provided between the second battery 16 and the connection point PB connected to the connection path LB in the second intra-system path LA2, and steps down the voltage to a voltage lower than the power supply voltage VA by the power supply from the first converter 12 to charge the second battery 16. When the second battery 16 is discharged, the second converter 26 boosts the voltage of the second battery 16 and applies the boosted voltage to the second load 36. That is, the second converter 26 is a bidirectional power converter capable of performing a step-up operation and a step-down operation and converting power when the second battery 16 is charged and discharged. The second battery 16 is a battery that can be charged with the power supply voltage VA of the first converter 12.

The control device 40 generates a first switching signal SC1 to switch the first switch SW1 based on the detection value of the current detection section 28, and outputs an instruction based on the first switching signal SC1 to the first switch SW1. The control device 40 generates the first control signal SD1 and the second control signal SD2 to control the operations of the first converter 12 and the second converter 26, and outputs a command based on the first control signal SD1 and the second control signal SD2 to the first converter 12 and the second converter 26. The operating state and the operation stop state of the first converter 12 and the second converter 26 are switched by the first control signal SD1 and the second control signal SD 2. The operating state of the second converter 26 includes a charging operating state in which the second battery 16 is charged and a discharging operating state in which the second battery 16 is discharged.

The control device 40 is connected to and controls the notification unit 44, the IG switch 45, and the input unit 46. The notification unit 44 is a device that visually or audibly notifies the driver, and is, for example, a display or a speaker provided in the vehicle interior. The IG switch 45 is a start switch of the vehicle. The control device 40 monitors the opening or closing of the IG switch 45. The input unit 46 is a device that receives an operation by the driver, and is, for example, a steering wheel, a lever, a button, a pedal, or a voice input device.

The control device 40 uses the above-described specific load 32 to perform manual driving and automatic driving of the vehicle. The control device 40 includes a well-known microcomputer constituted by a CPU, ROM, RAM, flash memory, and the like. The CPU refers to an arithmetic program or control data in the ROM to realize various functions for manual driving and automatic driving.

In addition, the manual driving indicates a state in which the vehicle is controlled to travel by the operation of the driver. The automated driving indicates a state in which the vehicle is controlled to travel according to the control content of the control device 40 without being operated by the driver. Specifically, the automated driving is automated driving at a level 3 or more among automated driving levels from level 0 to level 5, which are prescribed by the road traffic safety administration of transportation province (NHTSA) in the united states. The level 3 is a level at which the control device 40 controls both the steering operation and the acceleration/deceleration while observing the traveling environment.

The control device 40 can perform a driving assistance function such as LKA (Lane departure warning), LCA (Lane Change departure), PCS (Pre-Crash Safety) or the like using the specific load 32. Control device 40 can switch the driving mode of the vehicle between a first mode in which the driving assistance function is used and a second mode in which the driving assistance function is not used, and the vehicle can travel in each driving mode. The control device 40 switches the first mode and the second mode in accordance with a switching instruction of the driver input via the input unit 46. Here, the first mode includes a mode in which the driver manually drives the vehicle using the driving assistance function and a mode in which the vehicle is automatically driven. The second mode is a mode in which the driver manually drives the vehicle without using the driving assistance function.

In the first mode, control device 40 determines whether or not an abnormality has occurred in first system ES1 and second system ES2, and if it is determined that an abnormality has not occurred in either of systems ES1, ES2, it performs automatic driving and driving assistance of the vehicle using first load 34 and second load 36. Thus, the first load 34 and the second load 36 cooperatively perform one function required for the automatic driving and the driving assistance. In the present embodiment, the abnormality is a power failure abnormality such as a ground fault or a disconnection.

On the other hand, when it is determined that an abnormality has occurred in either of the systems ES1 and ES2, the first switch SW1 is turned off to electrically insulate the first system ES1 from the second system ES2. Thus, even when an abnormality occurs in one of the systems ES1 and ES2, the loads 34 and 36 of the other system ES1 and ES2 in which no abnormality occurs can be driven.

When the first switch SW1 is turned off in association with the occurrence of an abnormality in the first system ES1, the second system ES2 supplies electric power to the second load 36 by discharging the second battery 16 through the second converter 26. In the second converter 26, since power conversion is performed at the time of discharge, discharge is started after preparation processing for power conversion. Here, the preparation processing refers to, for example, processing for applying a predetermined current to a primary coil in a converter including an input-side primary coil and an output-side secondary coil. Therefore, a predetermined period TS is required from the start of the preparation process to the actual start of the discharge, and there is a possibility that the second system ES2 cannot be supplied with appropriate power during the predetermined period TS.

In the present embodiment, the first path LC1 and the second path LC2 provided in parallel with each other are provided between the connection point PB connected to the connection path LB in the second system ES2 and the second battery 16. The second converter 26 is provided in the first path LC1, and the second battery 16 is charged or discharged at a voltage higher than the threshold voltage Vth, which is the lower limit value of the driving voltage of the first load 34 and the second load 36, by the power conversion of the second converter 26.

In addition, in the second path LC2, the voltage of the second battery 16 can be applied to the first load 34 and the second load 36 bypassing the second converter 26. Specifically, the second path LC2 is provided with a switch unit 24. Hereinafter, for the sake of distinction, the switch unit 20 is referred to as a first switch unit 20, and the switch unit 24 is referred to as a second switch unit 24. The second switching section 24 is provided with a second switching element (hereinafter, simply referred to as a second switch) SW2 and a diode DA connected in series. In the second switch section 24, the second switch SW2 is provided at a position closer to the connection path LB than the diode DA.

The second switch SW2 opens or closes the second system ES2. In the present embodiment, a MOSFET is used as the second switch SW2. The control device 40 generates the second switching signal SC2 and outputs an instruction based on the second switching signal SC2 to the second switch SW2 to perform a switching operation on the second switch SW2. The diode DA is disposed such that the cathode is located on the connection point side with the connection path LB and the anode is located on the second battery 16 side. In the present embodiment, the second switch SW2 corresponds to a "battery switch".

In this case, when the electric power is supplied from the second battery 16 by the second system ES2 in association with the occurrence of an abnormality in the first system ES1, the second battery 16 is charged to a voltage higher than the threshold voltage Vth, which is the lower limit value of the driving voltage of the first load 34 and the second load 36. In the present embodiment, the control process of bypassing the second converter 26 and applying the threshold voltage Vth to the second load 36 is performed during the predetermined period TS required for the power conversion of the second converter 26 accompanying the discharge of the second battery 16. This enables appropriate power supply to loads 34 and 36 in power supply system 100 having a plurality of power supply systems.

Fig. 2 shows a flowchart of the limiting process of the present embodiment. When the IG switch 45 is closed, the control device 40 repeats the limiting process for each predetermined control cycle. At the beginning of the closing of the IG switch 45, the driving mode of the vehicle is set to the second mode. The first switch SW1 is closed, the second switch SW2 is opened, the first converter 12 is in an operating state, and the second converter 26 is in a charging operating state.

When the limiting process is started, first, in step S10, it is determined whether or not the driving mode of the vehicle is the second mode. If an affirmative determination is made in step S10, the remaining capacity SA of the second battery 16 is calculated in step S12. The remaining capacity SA is, for example, SOC (State Of Charge) indicating the State Of Charge Of the second battery 16. When the second battery 16 is in an energized state (charged state or discharged state), the remaining capacity SA is calculated using a current accumulated value that is a time-integrated value of charge-discharge current of the second battery 16.

In step S14, it is determined whether or not the remaining capacity SA calculated in step S12 is greater than a predetermined capacity threshold Sth. Here, the capacity threshold Sth is a capacity at which the voltage of the second battery 16 is higher than the threshold voltage Vth. When the remaining capacity SA of the second battery 16 is smaller than the capacity threshold Sth, the voltage of the second battery 16 is not higher than the threshold voltage Vth, and the precondition for the implementation of the first mode is not satisfied, and therefore a negative determination is made in step S14, and the process proceeds to steps S50 and S52.

On the other hand, when remaining capacity SA of second battery 16 is greater than capacity threshold Sth, the voltage of second battery 16 is higher than power supply voltage VA by a predetermined value or more, and the precondition for the implementation of the first mode is satisfied, so an affirmative determination is made in step S14. In this case, in step S16, the second converter 26 is controlled to switch between the charging operation state and the operation stop state as appropriate in accordance with the remaining capacity SA of the second battery 16. Next, in step S17, the second switch SW2 is closed. Next, in step S18, switching of the driving mode of the vehicle from the second mode to the first mode is permitted, and the limiting process is ended. The switching to the first mode is performed when a switching instruction such as an instruction to use the driving assistance function or an instruction to perform automatic driving is input from the driver via the input unit 46, for example. In the present embodiment, the process of step S18 corresponds to a "mode control unit".

On the other hand, if a negative determination is made in step S10, it is determined in step S20 whether or not the driver notification is in progress. Here, the driver notification makes the driver aware that an abnormality has occurred in either one of the first system ES1 and the second system ES2, and makes the driver aware of information to suspend the first mode, and facilitates switching to the second mode.

If a negative determination is made in step S20, it is determined in steps S22 and S24 that an abnormality has occurred in either one of the first system ES1 and the second system ES2. Specifically, in step S22, it is determined whether or not an abnormality has occurred in the first system ES1. If a negative determination is made in step S22, it is determined in step S24 whether or not an abnormality has occurred in the second system ES2. In the present embodiment, the process of step S22 corresponds to an "abnormality determination unit".

The occurrence of an abnormality can be determined based on the magnitude and direction of the inter-system current IA detected by the current detection unit 28. For example, when a ground fault occurs in the first system ES1, the direction of the inter-system current IA detected by the current detection unit 28 is a direction from the second system ES2 toward the first system ES1, and the magnitude of the inter-system current IA detected by the current detection unit 28 is equal to or greater than the predetermined current threshold Ith for ground fault determination. Therefore, the current flowing in the first system ES1 is equal to or greater than the current threshold Ith. For example, when a ground fault occurs in the second system ES2, the direction of the inter-system current IA detected by the current detection unit 28 is a direction from the first system ES1 toward the second system ES2, and the magnitude of the inter-system current IA detected by the current detection unit 28 is equal to or greater than the current threshold Ith. Therefore, the current flowing in the second system ES2 is equal to or greater than the current threshold Ith. Therefore, it is possible to determine which of the systems ES1 and ES2 the abnormality has occurred in, based on the magnitude and direction of the inter-system current IA detected by the current detection unit 28.

If it is determined that neither of the systems ES1 and ES2 has an abnormality, a negative determination is made in step S24. In this case, the limiting process is ended.

On the other hand, when it is determined that an abnormality has occurred in either of the systems ES1 and ES2, a process is performed in which the supply of electric power to the system side in which the abnormality has occurred is stopped, and the supply of electric power to the electric loads of the system in which the abnormality has not occurred is continued.

Specifically, when an affirmative determination is made in step S22, first, in step S26, it is determined whether or not the first switch SW1 is off. If a negative determination is made in step S26, the first switch SW1 is turned off in step S28. Next, in step S30, a command for bringing the first converter 12 into an operation stop state is output. This stops the supply of electric power to the first system ES1 in which the abnormality has occurred. In the present embodiment, the process of step S28 corresponds to a "state control unit".

Next, in step S32, a command is output to place the second converter 26 in a discharge operation state in which the voltage of the second battery 16 is boosted. Next, in step S34, after the instruction is output in step S32, the second switch SW2 is closed, and the control process is ended. The discharge of the second battery 16 by the second converter 26 ensures the supply of electric power to the second load 36.

On the other hand, if an affirmative determination is made in step S26, that is, if the processing in steps S28 to S34 has already been performed, it is determined in step S36 whether or not the load voltage VD applied to the second load 36 is equal to or higher than the predetermined target voltage Vtg. In addition, the load voltage VD is raised to the target voltage Vtg by the discharge of the second battery 16 by the second converter 26.

In the case where the load voltage VD is lower than the target voltage Vtg, a negative determination is made in step S36. In this case, the control process is ended, and the boosting of the load voltage VD by the second converter 26 is continued. On the other hand, when the load voltage VD is equal to or higher than the target voltage Vtg, an affirmative determination is made in step S36. In this case, in step S38, the second switch SW2 is turned off.

If an affirmative determination is made in step S24, first, in step S40, the first switch SW1 is turned off. As a result, the supply of electric power from the first converter 12 in the first system ES1 to the first load 34 is continued. Next, in step S42, a command for bringing the second converter 26 into an operation stop state is output.

Thereafter, in step S44, the information for stopping the first mode is notified to the driver via the notification unit 44, and the control process is ended.

If an affirmative determination is made in step S20, it is determined in step S46 whether or not an instruction to switch to the second mode is input from the driver via the input unit 46. That is, it is determined whether or not there is a response of the driver corresponding to the notification. If a negative determination is made in step S46, the control process is ended, and the vehicle continues to run in the first mode using the loads 34 and 36 on the system side where no abnormality has occurred.

On the other hand, if an affirmative determination is made in step S46, the driving mode of the vehicle is switched from the first mode to the second mode in step S48, and the control process is ended.

In steps S50 and S52, that is, when the driving mode of the vehicle is the second mode, it is determined that an abnormality has occurred in either one of the first line ES1 and the second line ES2. Specifically, in step S50, it is determined whether or not an abnormality has occurred in the first system ES1. If a negative determination is made in step S50, it is determined in step S52 whether or not an abnormality has occurred in the second system ES2.

If it is determined that neither of the systems ES1 and ES2 has an abnormality, a negative determination is made in step S52. In this case, the control process is terminated, and the vehicle continues to travel in the second mode.

On the other hand, when it is determined that an abnormality has occurred in either of the systems ES1 and ES2, a process is performed in which the supply of electric power to the system side in which the abnormality has occurred is stopped, and the supply of electric power to the electric loads of the system in which the abnormality has not occurred is continued.

Specifically, if an affirmative determination is made in step S50, first, in step S54, the first switch SW1 is turned off. Next, in step S56, a command for bringing the first converter 12 into an operation stop state is output. Next, in step S34, the second switch SW2 is closed, and the process proceeds to step S66. That is, in the second mode, when an abnormality occurs in the first system ES1, the opening and closing of the second converter 26 is not switched.

When an affirmative determination is made in step S52, the processing in steps S62 to S64 is performed. The processing in steps S62 to S64 is the same as the processing in steps S40 to S44, and therefore, description thereof is omitted.

Next, fig. 3 shows an example of the control process. Fig. 3 shows transitions of the power supply voltage VA and the load voltage VD when a ground fault abnormality (hereinafter, simply referred to as a ground fault) occurs in the first system ES1 while the vehicle is running in the first mode.

In fig. 3, (a) shows transition of the state of the IG switch 45, (B) shows transition of the driving mode of the vehicle, (C) shows transition of the open/closed state of the first switch SW1, and (D) shows transition of the open/closed state of the second switch SW2. Further, (E) shows changes in the operating state of the second converter 26, (F) shows changes in the power supply voltage VA at the first converter 12, and (G) shows changes in the load voltage VD at the second load 36. Further, (H) indicates a transition of the inter-system current IA, and (I) indicates a transition of the remaining capacity SA of the second battery 16. In fig. 3 (H), transition of the inter-system current IA is indicated by setting the inter-system current IA flowing from the second system ES2 to the first system ES1 to a positive direction.

As shown in fig. 3, during the off period of the IG switch 45 up to time t1, that is, in the inactive state of the power supply system 100, the first switch SW1 and the second switch SW2 are turned off, and the first converter 12 and the second converter 26 are switched to the operation stop state. Therefore, during the off period of the IG switch 45, the load voltage VD and the inter-system current IA are zero.

When the IG switch 45 is closed at time t1, the first switch SW1 is closed, and a command to switch the first converter 12 to the operating state and the second converter 26 to the charging operating state is output. As a result, the first converter 12 is switched to the operating state, and the power supply voltage VA and the load voltage VD are increased to the predetermined operating voltage VM, thereby enabling the vehicle to travel in the second mode. Here, the operating voltage VM is a voltage within a driving voltage range of the first load 34 and the second load 36, and is equal to the target voltage Vtg.

The second converter 26 is switched to the charging operation state, and the second battery 16 is charged by the power supply voltage VA of the first converter 12. Thereby, the voltage of the second battery 16 rises to the predetermined step-down voltage VL higher than the threshold voltage Vth (see fig. 3G).

When the remaining capacity SA of the second battery 16 increases and the remaining capacity SA becomes larger than the capacity threshold Sth, the driving mode of the vehicle can be switched from the second mode to the first mode at time t 2. Then, in accordance with a switching instruction from the driver to the first mode, switching is made to the first mode, and the second switch SW2 is closed. In the present embodiment, even after the switching to the first mode, the second converter 26 is maintained in the operating state, and the charging of the second battery 16 is continued. In the first mode, the charging current of the second battery 16 decreases with an increase in the remaining capacity SA, and the magnitude of the inter-system current IA decreases. When the remaining capacity SA reaches the full charge, the charge of the second battery 16 is temporarily stopped.

During traveling of the vehicle in the first mode, it is determined that a ground fault has occurred in either one of the first line ES1 and the second line ES2. When it is determined that the ground fault has not occurred in either of the systems ES1 and ES2, the first switch SW1 is maintained in the closed state. Thereby, electric power can be supplied from the first converter 12 and the first and second storage batteries 14 and 16 to the first and second loads 34 and 36, respectively. The power supply from the first converter 12 can be continued even in long-term autonomous driving, and the power supply from the first battery 14 and the second battery 16 can be performed with little voltage variation. As a result, during the period from time t2 to time t3, automatic driving and driving assistance using the first load 34 and the second load 36 are performed.

When it is determined that a ground fault has occurred in one of the systems ES1 and ES2, the first switch SW1 is closed. In fig. 3, at time t3, a ground fault occurs in the first system ES1. Thereby, the power supply voltage VA and the load voltage VD are reduced. In addition, the reduction speed of the load voltage VD is smaller than that of the power supply voltage VA due to the inductance component of the connection path LB.

The inter-system current IA increases, and then at time t4, the inter-system current IA becomes equal to or greater than the current threshold Ith. Thereby, it is determined that a ground fault has occurred in the first system ES1. In this case, at time t4, the first switch SW1 is turned off, and the first converter 12 is switched to the action stop state. Thereby, the inter-system current IA decreases.

At time t4, a command is output to switch second converter 26 to the discharge operation state in which the voltage of second battery 26 is boosted. Thereby, at the subsequent time t6, the discharge of the battery via the second converter 26 is started, and the load voltage VD is increased. Then, the second switch SW2 is closed during at least a part of the predetermined period TS from the time t4 to the time t 6. Thus, during the predetermined period TS, the step-down voltage VL, which is the voltage of the second battery 16, is applied to the second load 36 bypassing the second converter 26.

As shown by the broken line in fig. 3 (G), if the step-down voltage VL is not applied during the predetermined period TS, the load voltage VD becomes lower than the threshold voltage Vth at time t5 between time t4 and time t 6. Then, at time t7 after the start of discharge of the battery, the load voltage VD rises above the threshold voltage Vth. That is, in the voltage drop period TD from the time t5 to the time t7, the load voltage VD is lower than the threshold voltage Vth, and the power supply to the second load 36 is temporarily interrupted.

In the present embodiment, the step-down voltage VL is applied to the second load 36 during the predetermined period TS. Since the step-down voltage VL is set to a voltage higher than the threshold voltage Vth, the load voltage VD can be suppressed from being lowered from the threshold voltage Vth when an abnormality occurs in the first system ES1.

In particular, in the present embodiment, in the first mode, the second switch SW2 is maintained in a closed state. Therefore, as the load voltage VD decreases, the discharge from the second battery 16 via the second path LC2 is performed, and the electric power can be supplied to the second load 36 at an early stage.

At time t8 after the predetermined period TS has elapsed, that is, after the start of discharge of the second battery 16, when the load voltage VD rises to the target voltage Vtg, the second switch SW2 is turned off. This can suppress the second battery 16 from being charged with the load voltage VD.

Thereafter, when a switching instruction to the second mode is input from the driver via the input portion 46, the driving mode of the vehicle is switched from the first mode to the second mode at time t 9.

According to the present embodiment described in detail above, the following effects can be obtained.

In the present embodiment, the first path LC1 and the second path LC2 are provided in parallel with each other between the second battery 16 and the connection point PB connected to the connection path LB in the second system ES2. In the first path LC1, the second battery 16 is charged or discharged at a voltage higher than the threshold voltage Vth, which is the lower limit value of the drive voltage of the first load 34 and the second load 36, by the power conversion by the second converter 26. In addition, in the second path LC2, the voltage of the second battery 16 can be applied to the first load 34 and the second load 36 bypassing the second converter 26.

In this case, when the power supply from the second battery 16 is performed by the second system ES2 in association with the occurrence of an abnormality in the first system ES1, the second battery 16 is charged to a voltage higher than the threshold voltage Vth, which is the lower limit value of the driving voltage of the first load 34 and the second load 36, and the threshold voltage Vth can be applied to the second load 36 while bypassing the second converter 26 in the predetermined period TS required for the power conversion by the second converter 26. This enables appropriate power supply to loads 34 and 36 in power supply system 100 having a plurality of power supply systems.

In the present embodiment, the second path LC2 is provided with the second switch SW2, and when an abnormality occurs in the first system ES1, the second switch SW2 is closed in association with the output of the discharge command to the second converter 26. Specifically, the second switch SW2 is closed during a predetermined period TS from when a command to discharge the second battery 16 is output to the second converter 26 to when the discharge operation is started. As a result, when an abnormality occurs in the first system ES1, appropriate power can be supplied to the second load 36.

In the configuration in which the load voltage VD is set higher than the voltage of the second battery 16 when the second battery 16 is discharged, if the second switch SW2 is closed after the discharge of the second battery 16 is started, the rise of the load voltage VD may be delayed or the load voltage VD may become unstable due to the charge of the second battery 16 via the second path LC2. In this regard, in the present embodiment, since the second switch SW2 is turned off after the discharge operation is started, the load voltage VD can be appropriately increased.

The first load 34 and the second load 36 are loads that perform a function required for vehicle travel and a driving assistance function. Further, it is possible to switch between the first mode of running using the driving assistance function and the second mode of running not using the driving assistance function. In the present embodiment, switching of the vehicle running mode from the second mode to the first mode is permitted on the condition that the remaining capacity SA of the second battery 16 is a capacity in a state in which the voltage of the second battery 16 is higher than the lower limit value of the drive voltage of the first load 34 and the second load 36. Therefore, even if an abnormality occurs in the first system ES1 after the transition to the first mode, appropriate fail-safe processing can be performed thereafter.

(second embodiment)

Hereinafter, a second embodiment will be described focusing on differences from the first embodiment with reference to fig. 4 and 5.

In the present embodiment, as shown in fig. 4, the second switch unit 24 is different from the first embodiment in that it includes a third switch SW3 and a fourth switch SW4 connected in series. In the second switch section 24, the third switch SW3 is provided at a position closer to the connection path LB side than the fourth switch SW 4.

In this embodiment, MOSFETs as semiconductor switching elements are used as the third switch SW3 and the fourth switch SW 4. The third parasitic diode DA3 is connected in parallel with the third switch SW3, and the fourth parasitic diode DA4 is connected in parallel with the fourth switch SW 4. In the present embodiment, the third switch SW3 and the fourth switch SW4 are connected in series in such a manner that the directions of the third parasitic diode DA3 and the fourth parasitic diode DA4 are reversed from each other.

Specifically, the third parasitic diode DA3 is disposed such that the anode is positioned on the second battery 16 side and the cathode is positioned on the connection path LB side, and the fourth parasitic diode DA4 is disposed such that the anode is positioned on the connection path LB side and the cathode is positioned on the second battery 16 side. Therefore, the third parasitic diode DA3 restricts the flow of current from the connection point PB to the second battery 16 in the second path LC2, and the fourth parasitic diode DA4 restricts the flow of current from the second battery 16 to the connection point PB in the second path LC2. In the present embodiment, the third parasitic diode DA3 corresponds to a "rectifying element".

The control device 40 generates the third switching signal SC3 and the fourth switching signal SC3 in the control process, and outputs an instruction based on the third switching signal SC3 and the fourth switching signal SC3 to the third switch SW3 and the fourth switch SW4 to perform a switching operation on the third switch SW3 and the fourth switch SW 4.

Fig. 5 shows a flowchart of the control process of the present embodiment. In fig. 5, for convenience, the same processes as those shown in fig. 2 are assigned the same step numbers and the description thereof is omitted. Further, at the beginning of the closing of the IG switch 45, the third switch SW3 is opened and the fourth switch SW4 is closed.

In the control processing of the present embodiment, if an affirmative determination is made in step S22, it is determined in step S70 whether or not the second converter 26 is in the discharge operation state. If a negative determination is made in step S70, the processing in steps S28 to S32 is performed, and the control processing is ended. On the other hand, if an affirmative determination is made in step S70, that is, if the processing of steps S28 to S32 has already been performed, it is determined in step S72 whether or not the load voltage VD is higher than the step-down voltage VL of the second battery 16.

If the discharge operation of second converter 26 is not started and load voltage VD is equal to or lower than step-down voltage VL, a negative determination is made in step S72. In this case, the control process ends, and the discharge of the second battery 16 via the fourth switch SW4 and the third parasitic diode DA3 is continued in the second path LC2. On the other hand, when the discharge operation of the second converter 26 is started and the load voltage VD is higher than the step-down voltage VL, an affirmative determination is made in step S72. In this case, in step S74, it is determined whether or not the load voltage VD becomes equal to or higher than the target voltage Vtg.

In the case where the load voltage VD is lower than the target voltage Vtg, a negative determination is made in step S74. In this case, the third switch SW3 is turned on, that is, turned on in step S76, and the control process is ended. Thereby, in the second path LC2, the second battery 16 is discharged via the fourth switch SW4 and the third switch SW3. On the other hand, when the load voltage VD is equal to or higher than the target voltage Vtg, an affirmative determination is made in step S74. In this case, in step S78, the third switch SW3 and the fourth switch SW4 are turned off, and the process proceeds to step S44.

In addition, if an affirmative determination is made in step S24, the first switch SW1 and the fourth switch SW4 are turned off in step S80, and the process proceeds to step S64.

On the other hand, if an affirmative determination is made in step S50, the processing of steps S54 and S56 is performed, and then the fourth switch SW4 is turned off in step S82, and the process proceeds to step S60. In addition, if an affirmative determination is made in step S52, the first switch SW1 and the fourth switch SW4 are turned off in step S84, and the process proceeds to step S64.

Fig. 6 shows changes in the power supply voltage VA and the load voltage VD when a ground fault occurs in the first system ES1 while the vehicle is traveling in the first mode. In fig. 6, (D) shows transition of the open/close state of the third switch SW3, and (E) shows transition of the open/close state of the fourth switch SW 4. In addition, since (a) to (C) and (F) to (J) in fig. 6 are the same as (a) to (C) and (E) to (I) in fig. 3, descriptions thereof are omitted.

As shown in fig. 3, the third switch SW3 and the fourth switch SW4 are opened during the opening period of the IG switch 45 up to time t1, and the fourth switch SW4 is closed when the IG switch 45 is closed at time t 1. Even if the driving mode of the vehicle is switched to the first mode at time t2, it is determined that a ground fault has occurred in the first system ES1 at time t4, and the open-closed states of the third switch SW3 and the fourth switch SW4 are maintained. Further, at time t4, the fourth switch SW4 is closed, and the discharge from the second battery 16 via the third parasitic diode DA3 is enabled, so the discharge from the second battery 16 is performed as the load voltage VD decreases.

Then, the discharge of the battery via the second converter 26 is started at time t6, and the third switch SW3 is closed when the load voltage VD is higher than the step-down voltage VL of the second battery 16.

At a later time t8, when the load voltage VD rises to the target voltage Vtg, the third switch SW3 and the fourth switch SW4 are turned off.

According to the present embodiment described in detail above, the following effects can be obtained.

In the present embodiment, the third switch SW3 having the third parasitic diode DA3 is provided in the second path LC2. In the configuration in which the load voltage VD is made higher than the voltage of the second battery 16 when the second battery 16 is discharged, the third parasitic diode DA3 restricts the flow of current from the connection point PB to the second battery 16 on the second path LC2, and the second battery 16 having a rated voltage lower than the power supply voltage VA can be used to configure the power supply system 100. In the second system ES2, when an abnormality occurs in the first system ES1, the discharge from the second battery 16 is performed as the load voltage VD decreases, and it is possible to supply electric power to the second load 36 in advance without waiting for the predetermined period TS required for the step-up operation of the second converter 26.

When the third parasitic diode DA3 of the third switch SW3 is used as the rectifying element, there is a possibility that a voltage drop due to the forward voltage drop amount of the third parasitic diode DA3 or heat generation of the third parasitic diode DA3 due to energization may occur. In contrast, in the present embodiment, when an abnormality occurs in the first system ES1, the third switch SW3 is closed, whereby it is possible to suppress a voltage drop due to the forward voltage drop amount of the third parasitic diode DA3 and to suppress heat generation of the third parasitic diode DA 3.

In the present embodiment, the second path LC2 is provided with the fourth switch SW4 connected in series with the third switch SW3, and the direction of the third parasitic diode DA3 of the third switch SW3 in the second path LC2 is reverse to the direction of the fourth parasitic diode DA4 of the fourth switch SW 4. Thus, in the configuration using the third parasitic diode DA3 as the rectifying element, overdischarge of the second battery 16 when an abnormality occurs in the second system ES2 can be suppressed.

(other embodiments)

The present disclosure is not limited to the description of the above embodiments, and may be implemented as follows.

Each of the loads 34 and 36 may be, for example, the following device.

The running motor and the drive circuit thereof may apply the running power to the vehicle. In this case, the first load 34 and the second load 36 are, for example, a three-phase permanent magnet synchronous motor and a three-phase inverter device, respectively.

Or may be an anti-lock brake device that prevents the wheels from locking during braking. In this case, the first load 34 and the second load 36 are each, for example, an ABS actuator capable of independently adjusting the brake oil pressure at the time of braking.

The cruise control device may be configured to detect a preceding vehicle that is traveling ahead of the host vehicle, maintain a constant inter-vehicle distance from the preceding vehicle when the preceding vehicle is detected, and cause the host vehicle to travel at a preset vehicle speed when the preceding vehicle is not detected. In this case, the first load 34 and the second load 36 are, for example, millimeter-wave radars, respectively.

The loads 34 and 36 are not necessarily combined in the same configuration, and may be combined in different types of devices to achieve the same function. In addition, the first load 34 and the second load 36 may not be different loads, but may be the same load. That is, the first load 34 and the second load 36 may be the same load that receives power supply from both the first intra-system path LA1 and the second intra-system path LA 2.

The voltage generator of the first power supply is not limited to the converter, and may be an alternator. The first power supply may have only the first battery 14, for example, without having a voltage generator.

In the above-described embodiment, the predetermined period TS is exemplified by the period from the time t4 to the time t6, that is, the period from the output of the command for discharging the second battery 16 to the start of the discharge of the second battery 16 to the second converter 26, but the present invention is not limited to this. The period from time t4 to time t6 may be set in advance based on the internal resistance of second battery 16, the wiring resistance of first path LC1, or the like, but may vary depending on the temperature environment of power supply system 100 or the like. Therefore, in consideration of this variation, the predetermined period TS may be set to a period including a period from the time t4 to the time t6, that is, a period longer than a period from the time t4 to the time t 6.

In the second embodiment described above, an example is shown in which the rectifying element provided in the second path LC2 is the third parasitic diode DA3 of the third switch SW3, but the present invention is not limited thereto.

For example, as shown in fig. 7, the rectifier element may be a single diode element. As shown in fig. 7, in this embodiment, the second switch unit 24 includes only the diode DA as a single diode element. Note that the diode DA is the same as the diode DA of the first embodiment, and therefore, description thereof is omitted.

The rectifying element is not limited to a diode, and may be a thyristor.

In the above-described embodiment, the example in which the power supply system 100 is applied to the vehicle capable of traveling by the manual driving and the automatic driving is shown, but the invention is not limited thereto. The present invention can be applied to a vehicle that can travel only by automatic driving, such as a fully autonomous vehicle, and can also be applied to a vehicle that can travel only by manual driving.

For example, when the present invention is applied to a vehicle that can travel only by autonomous driving, if an abnormality occurs in one of the systems ES1 and ES2, the following process may be performed: the traveling of the vehicle is stopped by automatic driving using the loads 34 and 36 of the other systems ES1 and ES2 in which no abnormality occurs, or the vehicle is stopped after moving to a safe place.

Although the present disclosure has been described based on the embodiments, it should be understood that the present disclosure is not limited to the embodiments and configurations described above. The present disclosure also includes various modifications and variations within an equivalent range. In addition, various combinations and modes including only one element and one or more or less other combinations and modes also belong to the scope and the idea of the present disclosure.

Claims (6)

1. A power supply system, the power supply system (100) having:

an electrical load (34, 36);

a first system (ES 1) comprising a first power source (10, 12, 14) connected to the electrical load;

a second system (ES 2) comprising a second power source (16) connected to the electrical load; and

an inter-system switch (SW 1) provided in a connection path (LB) connecting the first system and the second system to each other,

the first power supply outputs a supply voltage capable of driving the electrical load,

the second power supply comprises a battery (16) chargeable by the supply voltage of the first power supply,

the power supply system includes:

an abnormality determination unit that determines whether or not an abnormality has occurred in the first system; and

a state control unit that turns off the inter-system switch when the abnormality determination unit determines that an abnormality has occurred,

a first path (LC 1) and a second path (LC 2) are provided in parallel with each other between a connection Point (PB) connected to the connection path in the second system and the second power supply,

a power converter (26) that performs power conversion at the time of charging of the storage battery and at the time of discharging of the storage battery by power supply from the first power source is provided in the first path,

the storage battery is charged to a voltage higher than a lower limit value of a driving voltage of the electric load by the power converter,

in the second path, the voltage of the storage battery can be applied to the electrical load bypassing the power converter.

2. The power supply system of claim 1,

a battery switch (SW 2) for opening or closing the second path is provided in the second path,

the power converter performs or stops charging and discharging of the storage battery in accordance with an instruction from the state control unit,

the state control unit opens the inter-system switch and outputs a command for discharging the battery to the power converter when the abnormality determination unit determines that an abnormality has occurred, and closes the battery switch for a predetermined period including a period from when the command is output to when the battery discharge is started.

3. The power supply system of claim 2,

the power converter performs a boosting operation of boosting a voltage of the battery when the battery is discharged, and the state control unit turns off the battery switch after the discharge of the battery is started.

4. The power supply system of claim 1,

the power converter performs a step-down operation of stepping down a voltage of the battery when the battery is charged and performs a step-up operation of stepping up the voltage of the battery when the battery is discharged,

a rectifying element (DA 3) that restricts the flow of current from the connection point to the battery in the second path is provided in the second path.

5. The power supply system of claim 4,

a semiconductor switching element (SW 3) having a parasitic diode is provided in the second path,

the parasitic diode is the rectifying element, and the state control unit turns on the semiconductor switching element when the abnormality determination unit determines that an abnormality has occurred.

6. The power supply system according to any one of claims 1 to 5,

the power supply system is installed in a power supply system of a vehicle,

the electric load is a load that implements at least one function required for running in the vehicle, and is a load that implements a driving assistance function of the vehicle,

the vehicle is capable of running in a first mode using the driving assistance function and running in a second mode not using the driving assistance function,

the power supply system includes a mode control unit that allows the traveling mode of the vehicle to be shifted from the second mode to the first mode on the condition that a state of charge of the battery is a state in which a voltage of the battery is higher than a lower limit value of a drive voltage of the electrical load.

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